Play the Pipe Organ is a quest given when you enter the ballroom.
Gus realises that the Pipe Organ is malfunctioning. The only way out of the Ballroom is at the top and Gus suggests that helping him would make things easier. When Mickey approaches the Organ, he asks if Mickey would help him. After agreeing, the Organ instructs Mickey to repeat the notes he plays by hitting the keys with the yellow note above them. After the song is played, the Organ thanks Mickey and clears the way to the attic and rewards him the Play a Tune pin.